Among the explorations which have been carried on in the United States, none possess a greater interest than those of Dr. M.W. Dickeson, in the south western states, chiefly in Mississippi, though in some instances extending to Alabama, Louisiana, and Texas. Dr. Dickeson has laid open or examined one hundred and fifty mounds and tumuli, of various dimensions and collected a vast number of interesting relics, which illustrate the customs and arts of the ancient people who built them. The mounds vary from three to ninety feet in height, and from twelve to three hundred feet in diameter at the base. The Seltzer Town mound contains a superficies of eight acres on its summit. On digging into it vast quantities of human skeletons were found, chiefly with their heads flattened, and measuring generally six feet in length. Numerous specimens of pottery, including finely finished vases filled with pigments, ashes, ornaments, and beads, were also found. The north side of this mound is supported with a wall two feet thick, of sun dried bricks, filled with grass, rushes and leaves. In order to ascertain whether this immense tumulus was artificial or not, Dr. Benbrook, sank a shaft forty two feet, and found it artificial or made ground to that depth. Immense quantities of bones, both of men and animals, among the latter the head of a huge bear, were thrown out. Other excavations were made in this tumulus with the same result, thus showing it to have been a vast mausoleum or cemetery of the ancient race. The mounds are generally in systems varying from seven to ten, which Dr. Dickeson has divided into six classes as follows: _out post_, _ramparts or walls_, _telegraphs or look outs_, _temples_, _cemeteries_, and _tent mounds_. The first is seldom more than thirty feet at the base by ten feet high. Their shape varies, presenting sometimes a pyramid, at others a cone, or rhomboid. Walls surround the second class, which are from ten to fifteen feet in heighth, the same across the top, and from forty to fifty feet at the base. The "_Look out_" mounds are seldom under sixty feet high. Of this class, Dr. Dickeson has examined upwards of ninety. They are generally on the summit of a hill, overlooking the bottom lands. Here they stand some three hundred feet above the bottom lands, commanding an extensive prospect, and in some instances one may see the peaks of several systems of mounds in the distance. The "_Temple mounds_" are seldom more than twenty feet high, and stratified with ashes, loam, gravel, &c. They all have an earthen floor. Dr. Dickeson has, but in a single instant, found a skeleton in these mounds, and in this, he thinks the subject a Choctaw Indian recently placed there. It lay in a horizontal position, differing from the usual mode of burial, which is the sitting posture.